With one exception, the four top-selling human growth hormone brands used to treat short stature have shown steady increases in U.S. sales although that might be at least partly the results of increased use in hormone-deficient adults:

This was Spencer Davies' parents' to-do list as they prepared to send him off to kindergarten:

•Buy school supplies.

•Get backpack.

•Check height of school toilets.

Spencer weighed only 32 pounds — just 6 pounds more than his year-old sister — when he entered kindergarten. Nearly 6, he wore toddler size 3 and 4 clothes. He was so short he had to stand on his mom's or dad's feet to reach toilets in public restrooms.

Laurie Davies, his mother, was relieved to find he could reach the elementary school toilets himself if he stood on tiptoe. Still, she and her husband worried about his height.

"He was so small, people thought he was a toddler," says Davies, who lives in Mauston, Wis. Strangers would stop and comment: "How old is he? He can talk so well."

His parents first took Spencer to pediatric endocrinologist David Allen of the University of Wisconsin-Madison at age 2½. Initial medical tests found nothing that might explain his size, such as growth hormone deficiency, Allen says.

But the Davieses asked Allen to prescribe growth hormone. Spencer began daily shots at 6½, placing him in the middle of a debate about whether being short is a disability requiring medical treatment.

That was 4½ years ago. Spencer, who will be 11 Nov. 21, now stands 4-foot-1. A straight-A student, he's a top-ranked wrestler in Wisconsin. He's still one of the shortest kids in the fifth grade, but, his mother says, "he's not a head shorter than everybody anymore. It's not such an obvious disparity."

Growing up is expensive

When the Davieses tried to get coverage for Spencer's treatment, human growth hormone wasn't yet approved for otherwise "normal" children who are extremely short, although doctors could prescribe it for them.

In 2003, though, the Food and Drug Administration gave Eli Lilly permission to market Humatrope, its human growth hormone, for the treatment of idiopathic — or unexplained — short stature, or ISS.

The FDA says children with ISS are off the bottom of the growth charts and have a predicted adult height of less than 4-foot-11 for girls and 5-foot-3 for boys. Yet, Allen notes, predicting adult height "is far from an exact science," and some kids may just be late bloomers.

Joyce Lee, a pediatric endocrinologist at the University of Michigan, says an estimated 400,000 children in the USA fit Lilly's definition of ISS. She says treating just one-tenth of them would cost $4 billion, given that the average total cost of treatment is $100,000.

According to Lee, that works out to about $50,000 per inch gained. (In the only trial that's randomly assigned children with ISS to a placebo or to growth hormone, the hormone group's final adult height was, on average, about 1.5 inches higher than the placebo group's.)

Lee wonders whether that's money well spent. Growth hormone seems to be fairly safe, but what's to be gained other than a couple of inches? "There's no evidence that short children have poor psychosocial functioning, poor quality of friendship," she says. As for research that suggests tall men earn more than short men, she says, the tall men are usually well over 6 feet, far beyond the reach of growth hormone treatment.

Sure, short children may be teased, says David Sandberg, director of child behavioral health at University of Michigan, but "research is pretty clear that it doesn't translate into distress or dysfunction." Besides, he notes, "growth hormone takes years to work."

Gender gap in height

If being short truly is a handicap, say for driving a car, Sandberg asks, why do treatment criteria differ for boys and girls?

"If we're talking about height cutoffs that allow a person to get around in society, then that cutoff would be the same for men and women."

In a paper last month in the Archives of Pediatric & Adolescent Medicine, Lee and colleague Joel Howell suggest that the different treatments for short boys and girls stem from the perception that women should marry up.

Until the 1990s, some doctors gave tall girls estrogen to stunt their growth so they wouldn't tower over males, Lee says. Safety concerns and increased social value of height for girls ended this practice.

Now, twice as many boys as girls are treated with growth hormone, Lee and Howell write, noting that it has replaced estrogen therapy "as a means for preventing what was and might still be considered the union most offensive to taste," that of a tall woman and a short man.

Laurie Davies is 5-foot-2, and her husband is 5-foot-4 — both of which are below average.

"I don't think it's as big of an issue for women," she says. "People think you're cute. I think it's harder for a man. A tiny man is going to have a lot rougher time in the business world than a tiny woman."

Spencer could continue treatment until the growth plates at the end of his long bones fuse.

"We just wanted to do everything within our power to give him the best opportunity that we can," Davies says.